Recommended upgrade to laser table

The laser bed which typically comes standard with the Chinese laser cutters is usually a very thin sheet which has been riveted or screwed in carelessly. This will cause it to be warped from the first day of purchase. This is going to make it extremely hard to work on materials such as fabric, paper, and even thin wood. The following is a mod I made which turned the machine from a toy to something with enough reliability to be used in a small business setting.

I did this mod a few months ago so don't have many pictures. It should be easy enough to work out how to do it yourself though. First step is to remove the current aluminium sheet and get rid of it. This will require undoing a fair bit of the mounts for the table screws. Now is a good time to consider upgrading these mounts too if they are a bit sloppy. I made the new table plate out of 3mm thick aluminium. I used the old screw hole placements, and made sure to drill out plenty of holes for ventilation. The mounting screws have been countersunk so any oversized materials can still be laid down flat.

If you look closely at the picture of the table you can see I have drilled and tapped 7 small M3 holes along the left side and along the top below the first row of air holes. These holes have been made just outside where I had previously identified the x=0 and y=0 edge of the working area. So what I can do is screw in a piece of A3 acrylic sheet, and then cut along the border leaving behind a handy zero reference edge. This is an immensely useful thing to do, as it now allows me to line materials up accurately on the table and use the software to cut in absolute dimensions to get my jobs done exactly where I tell it. You can see in the last picture below I have also cut out a few spacers and triangles which will also be useful for lining stuff up.

Not only is it a very rigid base, but it is very easy to scrub clean (essential if you work with leather or wood). The only thing I would do different next time is make it out of steel, as being magnetic would also be really useful for pinning stuff down like fabric. But as it is, until you make this mod your machine is nothing but a toy.

Making sure the table is level is critical to getting an even cut over the entire work area. The good thing is that it is the simplest alignment procedure you will perform on the machine. Don't get a spirit level - we want to align the table relative to the rails, not the earth. All you need is something like an engineering square and you have all you need.

First somewhere down in the lower depths of the machine you should find all 4 corner screws are linked with something like a timing belt. If you undo the tensioner you will be able to release the belt and then all 4 screws will be free to be manipulated individually. While you are down below you may want to think about vacuuming the junk at the bottom too...

Now go back to the top of the table. If you z-axis is motor controlled you may need to loosen the coupler to continue. Using your square as a height gauge, go to one corner and manipulate the screw by hand until you get the top of the slide rail lined up to the square like I have done in the 3rd picture below. You can see how an engineer's square is the perfect tool for this, otherwise you need to make some similar sort of height gauge. Now go around to each corner and set each screw to the same reference height. Make sure to double check, as sometimes the timing belt can engage a little bit and move one of the other screws while your working on another. Once all 4 measure up good, go back under the table and re-position the tensioner. You now have a perfectly aligned table!